The overall objectives of this pilot study are to determine the feasibility of developing a nonhuman primate model for research on the etiology of Chagas' disease, to contribute to understanding the clinical condition of nonhuman primates that are naturally infected with Trypanosoma cruzi (the causative agent of Chagas' disease), and to protect against the use of T cruzi infected baboons as organ donors for xenotransplantation. The project will involve surveying 2,600 baboons for seropositivity to determine age-specific, sex-specific, and housing-specific prevalences of T. cruzi infection. The project will determine ages of seroconversion. and the heritability of seropositivity. The chromosomal location of polymorphic genes that confer differential susceptibility to T. cruzi infection will be sought by linkage analysis using 330 microsatellite markers already typed in the pedigreed baboons. The pathology of seropositive animals will be carefully documented at necropsy. Results obtained from this pilot study are expected to justify its expansion into a major model development project. The validation of a naturally occurring nonhuman primate model of Chagas' disease will be a major accomplishment for future research purposes, will enable a better understanding of the clinical condition of animals at the Center, and will provide a means for preventing the inadvertent infection of humans with T. cruzi via xenotransplantation.